How Molecular Motors Work: Insights from the Molecular Machinst’s Toolbox

Dean Astumian, Dept. Physics, UMaine

Richard Feynman and Bill McClellan –A motor 1/64th of an inch on a side

http://www.pbs.org/newshour/rundown/three-share-nobel-prize-chemistry-building-worlds-tiniest-machines/

Nano-Car

Structure of the four wheeled molecule

Rotaxanes and Catenanes – Mechanically Interlocked Molecules (MIMs)

What is the “BIG” question?

how did complex matter arise and self-organize to form life?

Chemistry – Making, Measuring, and Modelling

Berthelot: La Chimie cree son objet (Chemistry creates it object)

Borromean Rings

PDB projections on the Dome

Catenane and GFP (Jellyfish Protein)

~ 2000 times / sec

@ RT in CD3COCD3

J. Am. Chem. Soc. 1991, 113, 5131

1991 A MOLECULAR SHUTTLE

1991

Motion

https://www.youtube.com/watch?v=-7AQVbrmzFw

https://www.youtube.com/watch?v=wJyUtbn0O5Y 1:15-1:30

https://www.youtube.com/watch?v=YAva4g3Pk6k

Daisy Chain Arrangement

Pallindromic Arrangement

KF =[ox]

[red] reduce

A B

oxidize

A B

K = [A−−B]

KB =[ox]

[red]

K′ = [A][B]

Keq

A--B A + B

+ e-

e- V2+ V●+

●

DNP

●

●

+ 2e-

2e- CBPQT4+ CBPQT2(●+)

K KBK′ KF

= Keq

A [B

A−−B ss

= KeqKFKB

i

j ss

= e−Δ𝐺ij eW𝒮n ij

Extension of equilibrium relations to non-equilibrium steady state

Coulombic

Barrier

Radical

Recognition

Site

Potentially

Steric

Barrier

Ring

Collecting

Chain

Initial Free Ring State Final Ring Resting State

Reduced State

Oxidized State

RED OX

Nature Nanotechnology 2015, 10, 547

MOLECULAR PUMP DESIGN BLUEPRINT

Bisradical Dication

Potentially

PUMPING ONE FOLLOWED BY TWO RINGS

Nature Nanotechnology 2015, 10, 547

0 1 2 3

ΔG≠2 = 23.1 kcal mol-1

Second Redox Cycle

Time / h

2nd 85%

77%

0 1 2 3

0.0

0.2

0.4

0.6

0.8

1.0

ΔG≠1 = 23.0 kcal mol-1

First Redox Cycle

1st 90%

RED

Zn

OX

NOPF6

AWAY

FROM

EQUILIBRIUM

PUMPING RINGS ON TO POLYMERS WITH DUAL PUMPS

K K K

K K

K K

Aox + Ared

Dox + [Dred ss

≈ 𝐾DI,red𝐾IA,ox = e−∆𝐺oute∆𝐺−∆𝐺∗

k k k k k k k k k k k k

k k

k k

k k

k k

Aox + Ared

Dox + [Dred ss

= e−∆𝐺out1 + sDe∆μ 1 + sI

1 + sD 1 + sIe∆μ

= e−∆𝐺outq + e∆μ + L

1 + qe∆μ + L

q =𝑘I2ox 𝑘𝐷1

ox

𝑘I1ox 𝑘𝐷2

ox

FLASHING ENERGY RATCHET

+

+

+

+

ΔE

J. Am. Chem. Soc. 2013, 135, 18609

Reduction

Directionally Controlled

Dethreading

Oxidation Relaxation

Directionally Controlled

Threading

J. Am. Chem. Soc. 2013, 135, 18609.

Bacteriorhodopsin

TAKING INSPIRATION FROM NATURE

Steric

Barrier

IPP

Recognition

Site

DNP

Coulombic

Barrier

PY+

Molecular Pump Prototype

Reduction

Oxidation

CHEMISTRY AWAY-FROM-EQUILIBRIUM

Artificial Molecular Pump

Nature Nanotechnology

2015, 10, 547

WHAT ARE SOME OF

THE BIG QUESTIONS?

What are the

consequences

of

dissipation

on

materials

properties?

How do we

design systems

that operate

repetitively

and

progressively

away-from-equilibrium?

Slide-Ring Gels

Kohzo Ito and Kazuaki Kato